Quantum Interference Devices (QIDs) may be used as an alternative to thermionically-injected FETs as a means of implementing low-power, high-performance combinatorial logic. The principle of operation of a QID is analogous to the optical Mach-Zender interferometer. For example, a QID may operate by splitting an electron wave into two arms and rejoining these arms at the output. The wavelength of the electrons in one or both of the arms may be modulated by a gate electrode. By modulating the wavelengths, constructive or destructive interference can be achieved at the output. For optimal interference, the energy of electrons entering the QID should be uniform.
Quantum interference devices are also discussed, for example, in U.S. Pat. No. 5,130,766, U.S. Pat. No. 5,497,015, U.S. Pat. No. 7,786,472, European Patent Publication EP0381591, and European Patent Publication EP0493258.